$(document).ready(function() {
    function isPlaceholder() {
        var input = document.createElement('input');
        return 'placeholder' in input;
    }

    if (!isPlaceholder()) {//不支持placeholder 用jquery来完成  
        $(document).ready(function() {
            if (!isPlaceholder()) {
                $("input").not("input[type='password']").each(//把input绑定事件 排除password框  
                        function() {
                            if ($(this).val() === "" && $(this).attr("placeholder") !== "") {
                                $(this).val($(this).attr("placeholder"));
                                $(this).focus(function() {
                                    if ($(this).val() === $(this).attr("placeholder"))
                                        $(this).val("");
                                });
                                $(this).blur(function() {
                                    if ($(this).val() === "")
                                        $(this).val($(this).attr("placeholder"));
                                });
                            }
                        });
                //对password框的特殊处理1.创建一个text框 2获取焦点和失去焦点的时候切换  
                var pwdField = $("input[type=password]");
                var pwdVal = pwdField.attr('placeholder');
                pwdField.after('<input id="pwdPlaceholder" class="marginRight5 loginText paddingLeft5" type="text" value=' + pwdVal + ' autocomplete="off" />');
                var pwdPlaceholder = $('#pwdPlaceholder');
                pwdPlaceholder.show();
                pwdField.hide();

                pwdPlaceholder.focus(function() {
                    pwdPlaceholder.hide();
                    pwdField.show();
                    pwdField.focus();
                });

                pwdField.blur(function() {
                    if (pwdField.val() === '') {
                        pwdPlaceholder.show();
                        pwdField.hide();
                    }
                });

            }
        });

    }
})